In recent years, research has been conducted on methods for efficiently generating the plant hormone, ethylene, having various physiological effects, by spraying or irrigating plants with one or more types of substances selected from yeast extracts extracted from yeast or methionine (The Society for Chemical Regulation of Plants (1993), Abstract of Research Presentations, p. 114-115 and Japanese Patent Laid-Open Publication No. Hei7-285816) . In addition, it has been clearly demonstrated that dissolving one or more types of substances selected from yeast extracts or methionine and sprinkling on rice stems and leaves or irrigating underground areas has the effect of promoting the generation of phytoalexin and inhibiting rice blast (specification of Japanese Patent Application No.Hei7-353132, Bioscience, Biotechnology, and Agrochemistry, 1997, Vol. 71, p. 125).
However, since typically obtainable yeast extracts are in the form of dry fine powders and pellets, when applying to a field, they must first be dissolved in a suitable solvent such as water, thereby resulting in the problem of requiring both time and trouble for their dissolution and spraying. In addition, in the case of dissolving powdered yeast extract in water, and in the case of a yeast extract being obtained not in the form of a powder but rather in the form of a solution by dissolving in a suitable solvent such as water in advance, there were disadvantages in terms of storage caused by contamination by sundry germs making the liquid susceptible to putrefaction and deterioration.
In addition, methionine, a precursor of ethylene that is known to further increase ethylene production either by using alone or by mixing with yeast extract (Japanese Patent Laid-Open Publication No.Hei7-285817), also has poor solubility and diffusivity resulting in the problem of requiring considerable time and trouble in the case of using by dissolving in water.
On the other hand, rice paddy herbicidal tablets or capsules containing herbicide ingredients, surface active agents, foaming agents, binders and so forth (Japanese Patent Laid-Open Publication No.Hei3-223203), effervescent agricultural chemical preparations for application to rice paddies consisting of agricultural chemical active ingredients, carbonates, water-soluble solid acids and high boiling point solvents (Japanese Patent Laid-Open Publication No.Hei5-85901) and stabilized effervescent agricultural chemical preparations consisting of agricultural chemical active ingredients, carbonates or hydrogencarbonates, solid acids and boric oxide (Japanese Patent Laid-Open Publication No.Hei6-211604) have been proposed.
The object of the present invention is to provide an effervescent preparation for plants using yeast extract in the form of dry fine powder or pellets that can be easily dissolved and diffused when applying to a field, which has good storage stability by being resistant to putrefaction and deterioration caused by contamination by sundry germs in comparison with the case of dissolving in water and so forth, is handled easily, and can be applied to watered rice paddies directly by throwing, thereby enabling shortening of working time and conservation of manpower.
Moreover, another object of the present invention is to provide an effervescent preparation for plants containing methionine, which has poor solubility and diffusivity in water in the same manner as yeast extract, either alone or as a mixture with yeast extract, which in addition to having characteristics like those described above, is able to eliminate the trouble of dissolving in water.